Method and apparatus for drilling

ABSTRACT

A drill bit constructed to provide the simultaneous action of bit teeth mechanically moving the formation and a hydraulic force aiding the movement which is accomplished by channeling fluid down the drill bit cone shank through passages on the face of the cone, and inwardly between the teeth which are in contact with the formation.

[56] References Cited UNITED STATES PATENTS John D. Bennett Rlchardlon, Tex. 869,083

United States Patent [72] Inventor [2l] Appl. No.

PATENTEUNUV 9 ISH 3 518,6 8 2 snm 1 uf 2 I /NvE/VTOR "32 JOHN D. BENNETT F'IG. 2. ArToR/VEY PATENTEDNUV 9 |971 snm 2 or 2 F' I G. 3

/N VEN TOI? JOHN D. BENNETT ATTORNEY METHOD AND APPARATUS FOR DRILLING BACKGROUND OF TI-IE INVENTION This invention relates to a method and apparatus for eicient removal of wellbore cuttings by utilizing a new type of drill bit. At the present time, most drill bits are remarkably similar, having three cones attached to legs or shanks comprising the lower portion of the drill bit housing. These cones are ringed with teeth which partially intermesh with the teeth of the adjacent cones. Located between the upper portion of the shanks are generally nozzles through which drilling fluid passes to remove cuttings separated by the drill bit teeth. These nozzles are housed in nozzle bosses which causes a bulge of the housing between the legs. This describes the wellknown jet bit. The drilling mud flows through the interior of the drill pipe into the drill bit and through the nozzles, exiting the drill bit several inches above the formation surface. As a result, the drilling fluid descends directly to the floor of the wellbore. At this point, the fluid is supposed to lift the cuttings and return them to the surface of the ground. Laboratory tests have shown that this drilling fluid exerts a strong holddown force on the cuttings, thereby aggravating the work required by the drill bit. This holddown force is due in no small part to the angle at which the drilling fluid contacts the cuttings, since the fluid flow is downward, rather than sideways or from below. Another problem associated with this type of drilling bit is the lack of space for the cuttings to return to the surface. As presently constructed, the area occupied by the legs or shanks to which the cones are attached and the bosses in which the nozzles are held, take up most of the space between the drill bit and the hole. These two factors of a drilling fluid holddown force and the lack of space for the cuttings to return, result in fairly poor cuttings removal. Additionally, the drilling fluid must be expelled from the nozzles at a pressure of around 2,000 p.s.i. to get the proper jetting action. Such high pressure results in high repair costs for the mud pump.

The predecessor to the jet bit described above operates similarly, except the drilling fluid exits the drill bit housing from the center of the housing and strikes the drill bit teeth when they are located l80 from the bottom of the borehole. This bit has the disadvantage of the drilling fluid exerting a holddown force on the formation being cut as well as the fluid acting as a destructive force due to its abrasive action as it strikes the cones. The fluid exits high above the formation face and thus has no jetting effect.

lt is an object of the present invention to provide a new and improved drilling bit.

SUMMARY OF THE INVENTION With this object in view, the present invention contemplates providing a bit having a passageway for drilling fluids wherein the fluid passes through the drill bit housing to a point near the exterior wall of the drill bit leg. The fluid then descends to the bottom of the borehole where the fluid is directed, by the borehole and the passageway, between the teeth engaging the formation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a view of the bottom of a drill bit as it would engage the formation;

FIG. 2 is a side view of one ofthe legs ofthe drill bit; and

FIG. 3 is a cross-sectional view of a drill bit engaging the formation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. l of the drawings, the bottom view of a drill bit is shown. The cones 14 have teeth 12 attached thereon. Formation wall 18 is shown to illustrate the magnitude of the crosshatched area 16 formerly occupied by the nozzles and nozzle bosses of a standard jet bit and how the elimination of the nozzles and nozzle bosses greatly increases the area through which the drilling fluid can return to the surface. Fluid exits 17 (shown by dotted line) are illustrated to show the centralizing effects of fluid ejeeting in a restricted area in spaced longitudinal channels about the periphery of the bit. As the drill bit leans to one side of the hole, the space 19 between the formation wall and the drill bit decreases. As this space decreases, the pressure exerted by the drilling fluid increases, and the pressure on the other legs or shanks decreases due to an enlargement of the area upon which the drilling fluid acts. This relationship tends to keep the bit straight in the hole, thereby ameliorating crooked hole problems.

Referring next to FIG. 2, a side view of a drill bit is shown. Housing 2l has legs or shanks 22 formed therein as well as threaded connector 20. Located on leg 22 are cones 14 having teeth 12 formed thereon. The cones 14 are attached to journals (not shown) located on the lower part of each leg or shank 22. Upper fluid exit 30 is located on the legs 22 near the end located closest to the threaded connector. This exit is the end of a passageway 26 which interconnects to the interior wall 27 of the housing 21 with channels 34 extending from the upper fluid exits 30 down the length of legs 22 to a point adjacent the cone 14. The interior wall 27 communicates with the central passage extending through the drill pipe for passing drilling fluids to the bit. The cone 14 has grooves 32 between adjacent teeth on the cone. As drilling fluid flows down the drill pipe to the drill bit it passes through the passageway 26 in the housing and exits at 30. The fluid then proceeds down the channels 34 to communicate with the grooves 32 between adjacent teeth. At this point the sides and bottom ofthe borehole direct the drilling fluid between adjacent teeth in contact with the formation, creating a flushing action on the cuttings which is directed from the side, thereby eliminating substantially the holddown force of the drilling fluid. Additionally, the flushing action of the fluid between adjacent teeth contacting the formation operates to keep the teeth clean of formation cuttings. The channels 34 are sufficiently wide to be in communication with at least one groove 32 at all times. This is important when the cones are not rotating so that the fluid has a path to follow when the bit is not rotating on the bottom of the borehole.

The action of the drilling fluid on the fonnation may best be understood by referring to FIG. 3 which shows a cross section of the drill bit and the fonnation. Drilling fluid descends down the drill string (not shown) to the interior 36 of the drill bit housing 21. Atthe lower part of the interior of the housing are located passageways 26 which are well below threaded connector 20. Passageway 26 connects to channel 34 located on the exterior wall of the leg or shank 22. A drilling fluid exits the housing 21 through'passageway 26 at upper fluid exit 30, descends channel 34, and exits between adjacent teeth on the cone 12 in contact with the bottom of the borehole. The formation wall 18 in combination with channel 34 defines an enclosed passageway for the drilling fluid. When the drilling fluid strikes the bottom of the borehole, itis directed sideways between the teeth 12. Due to the centralizing tendencies of the fluid pressure acting on three sides of the drill bit, there is no problem with retaining a straight hole. As the area occupied by channel 34 increases, the pressure exerted by the drilling fluid decreases. Conversely, the area occupied by opposing channels would decrease and the drilling fluid would accordingly exert relatively more pressure at those points. Thus when the drill bit leans toward one side of the borehole, the pressure exerted by the drilling fluid increases and forces it away from that side. Thus it can be seen that the drill bit as presented by applicant will have the effect of centralizing the drill bit and thus result in a straighter hole. Additionally, the exit of drilling fluid adjacent the teeth 12 which are in contact with the formation has the effect of cleaning the teeth as well as substantially eliminating the holddown force of the drilling fluid on the cuttings. Also the drilling fluid is applied to the cutting at the precise moment of the shearing of the formation. Said flushing action is from a point at the side of the cutting, rather than exerted in a downward direction on the cutting, thereby enhancing the removal of the cutting. Additionally, as illustrated by the crosshatched area 16 of FIG. l, the passageways for exit of the drilling fluid and its return to the surface are greatly increased, resulting in improved circulation of the drilling fluid. The combination of increasing the area for drilling fluids return by eliminating the nozzles and nozzle bosses and directing the drilling fluid to a point between adjacent teeth in contact with the bottom of the borehole, allows use of drilling fluids at a pressure much less than that required for jet bits. The lower pressure results in a large savings in maintenance cost of the mud pumps. Maintenance costs of mud pumps rise geometrically with increased pressure. Substantial elimination of the cuttings holddown force, improved circulation, and hydraulic flushing action would result in a significant increase in drilling rate.

While particular embodiments ofthe present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in this description is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

l. A drill bit for use in drilling into earthlike formations including at least one rotating member having a plurality of adjacent teeth; and conduit means to provide a substantially enclosed cuttings removal fluid flow path having a flow path exit directly adjacent the teeth of said rotating member which are in contact with said earthlike formations.

2. A drill bit for use in drilling into earthlike formations comprising: at least one shank with a cone attached thereto, said cone having a plurality of teeth thereon; and means for providing a substantially confined cuttings removal fluid flow path having an exit directly between adjacent teeth of the cone when said adjacent teeth are in contact with said earthlike formation.

3. The drill bit of claim 2 wherein the fluid flow path means includes a passageway located in the upper portion of each shank extending through the wall of the shank.

4. The drill bit of claim 3 wherein the fluid flow path includes a channel extending from the exit of said passageway to a point adjacent the cone.

5. The drill bit of claim 3 wherein the edge portion of the cone located adjacent to the shank is grooved between adjacent teeth of each cone so that the channel located on the shank is aligned with said groove between adjacent teeth when said teeth are in contact with the earthlike formation.

6. A drill bit for use in drilling into earthlike fonnations including: atleast one shanklike protrusion; a cutter attached to each shank with adjacent teeth thereon; means to direct a cuttings removal fluid through the wall of the shanklike protrusion; and channel means on said protrusion to direct said fluid to a point between that shank's adjacent cutter teeth in contact with said earthlike formations.

7. A drill bit for use in drilling into earthlike formations comprising: a hollow body with a shank formed in the lower portion thereof; a journal formed in the lower portion of said shank; a cone with teeth thereon attached to the journal; means to pass a fluid from the interior to the exterior of the body, forming a fluids exit on the body; and means to direct the flow of fluid from the exit on the body down the shank to a point adjacent the cone teeth in contact with the earthlike formations.

8. The drill bit of claim 7 wherein the means to direct the flow of fluid down the shank consists of a channel extending vertically along the outside of the shank and together with the borehole forms a substantially enclosed passageway from said fluids exit to a point adjacent the teeth in contact with the earthlike formation.

9. The drill bit of claim 8 wherein the means to pass a fluid from the interior of the body to the exterior of the body comprises an opening through the wall of the body.

l0. The drill bit of claim 9 wherein the opening is aligned with the channel in the shank so as to provide a continuous path for fluids from the interior of the body to the teeth in contact with the earthlike formations. l

ll. The method of removing cuttings from a well comprising: pumping drilling fluid down the interior of drill pipe to a drill bit, and passing the drilling fluid out of the drill bit and through a substantially enclosed passageway to a point adjacent the cutting edge ofthe drill bit when said edge is in position for contacting the formation to be cut.

12. The method of claim 1l including moving the drilling fluid through the wall of the drill bit housing and down each shank of the bit to a point between the teeth of each shank which are positioned for contact with the bottom of the borehole.

13. The method of removing cuttings from a wellbore comprising: pumping drilling fluid through the drill pipe to a drill bit; passing said drilling fluid through a substantially enclosed passageway formed by a channel in the exterior wall of the drill bit and the formation wall; and subsequently directing the drilling fluid substantially laterally between the drill bit teeth engaging the formation by said fluid deflecting against the sidewall and bottom of the formation. 

2. A drill bit for use in drilling into earthlike formations comprising: at least one shank with a cone attached thereto, said cone having a plurality of teeth thereon; and means for providing a substantially confined cuttings removal fluid flow path having an exit directly between adjacent teeth of the cone when said adjacent teeth are in contact with said earthlike formation.
 3. The drill bit of claim 2 wherein the fluid flow path means includes a passageway located in the upper portion of each shank extending through the wall of the shank.
 4. The drill bit of claim 3 wherein the fluid flow path includes a channel extending from the exit of said passageway to a point adjacent the cone.
 5. The drill bit of claim 3 wherein the edge portion of the cone located adjacent to the shank is grooved between adjacent teeth of each cone so that the channel located on the shank is aligned with said groove between adjacent teeth when said teeth are in contact with the earthlike formation.
 6. A drill bit for use in drilling into earthlike formations including: at least one shanklike protrusion; a cutter attaChed to each shank with adjacent teeth thereon; means to direct a cuttings removal fluid through the wall of the shanklike protrusion; and channel means on said protrusion to direct said fluid to a point between that shank''s adjacent cutter teeth in contact with said earthlike formations.
 7. A drill bit for use in drilling into earthlike formations comprising: a hollow body with a shank formed in the lower portion thereof; a journal formed in the lower portion of said shank; a cone with teeth thereon attached to the journal; means to pass a fluid from the interior to the exterior of the body, forming a fluids exit on the body; and means to direct the flow of fluid from the exit on the body down the shank to a point adjacent the cone teeth in contact with the earthlike formations.
 8. The drill bit of claim 7 wherein the means to direct the flow of fluid down the shank consists of a channel extending vertically along the outside of the shank and together with the borehole forms a substantially enclosed passageway from said fluids exit to a point adjacent the teeth in contact with the earthlike formation.
 9. The drill bit of claim 8 wherein the means to pass a fluid from the interior of the body to the exterior of the body comprises an opening through the wall of the body.
 10. The drill bit of claim 9 wherein the opening is aligned with the channel in the shank so as to provide a continuous path for fluids from the interior of the body to the teeth in contact with the earthlike formations.
 11. The method of removing cuttings from a well comprising: pumping drilling fluid down the interior of drill pipe to a drill bit, and passing the drilling fluid out of the drill bit and through a substantially enclosed passageway to a point adjacent the cutting edge of the drill bit when said edge is in position for contacting the formation to be cut.
 12. The method of claim 11 including moving the drilling fluid through the wall of the drill bit housing and down each shank of the bit to a point between the teeth of each shank which are positioned for contact with the bottom of the borehole.
 13. The method of removing cuttings from a wellbore comprising: pumping drilling fluid through the drill pipe to a drill bit; passing said drilling fluid through a substantially enclosed passageway formed by a channel in the exterior wall of the drill bit and the formation wall; and subsequently directing the drilling fluid substantially laterally between the drill bit teeth engaging the formation by said fluid deflecting against the sidewall and bottom of the formation. 